Asphalt road pavements are being subjected to increasingly severe load stress. The repeated deflection of the road pavement causes elastic-type failure and fatigue failure in the pavement, which manifests itself in the form of pavement surface cracking and fracturing patterns. Conventional repair methods involve asphalt overlays, or replacement of the pavement surface.
A variety of paving grade asphalt compositions have been developed for the purpose of providing improved physical and mechanical properties in pavements under heavy traffic loads. Illustrative of these developments are the asphalt compositions disclosed in U.S. Pat. Nos. 2,871,212; 3,338,849; 3,374,104; 3,821,144; 3,879,323; 4,105,612; and the like.
Also of increasing importance for reasons of economy and convenience are methods and materials for repairing and surfacing broken asphalt pavements. An important objective has been the development of materials for repair of asphalt pavements which exhibit increased flexibility and resistance to fatigue failure. Efforts to provide asphaltic binder materials with the desired elastomeric properties for asphalt pavement repair are typified by the technology of U.S. Pat. Nos. 2,310,972; 3,578,001; 2,700,655; 3,049,836; 3,253,521; 3,270,631; and 3,340,780.
U.S. Pat. No. 3,891,585 discloses an elastomeric pavement repair material which consists essentially of a jellied blend of a paving grade asphalt and a non-oil resistant asphalt-soluble rubber.
U.S. Pat. No. 3,919,148 discloses an elastomeric pavement repair material which is the reaction product of paving grade asphalt, asphalt-soluble rubber, and a low viscosity asphalt solvent.
U.S. Pat. No. 4,021,393 describes an elastomeric pavement repair material which is the reaction product of paving grade asphalt, non-oil resistant rubber, and petroleum maltenes.
There remains a need for an asphaltic cement material adapted for repair of asphalt pavements which is economical and conveniently workable under road repair conditions, and which exhibits an improved combination of elasticity and wear resistance properties.
Accordingly, it is a main object of this invention to provide an improved asphaltic binder composition adapted for the repairing and surfacing of distressed asphalt pavement surfaces.
It is another object of this invention to provide a novel asphaltic composition which is composed of low value petroleum refinery residuum and scrap polymeric material.
It is a further object of this invention to provide a process for repairing and surfacing broken pavements, in which process the aged asphalt of the pavement surface becomes dissolved and incorporated into a liquid binder composition which is applied to the pavement surface as a repair vehicle.
Other objects and advantages of the present invention shall become apparent from the accompanying description and disclosure.